Overlap junctions for superconducting quantum electronics and amplifiers
Mustafa Bal, Junling Long, Ruichen Zhao, Haozhi Wang, Sungoh Park, Corey Rae Harrington McRae, Tongyu Zhao, Russell E. Lake, V. Yu. Monarkha, Slawomir Simbierowicz, Daniil Frolov, Roman Pilipenko, Silvia Zorzetti, Alexander Romanenko, Chuan-Hong Liu, Robert McDermott, David P. Pappas · Applied Physics Letters · 2021
Due to their unique properties as lossless, nonlinear circuit elements, Josephson junctions lie at the heart of superconducting quantum information processing. Previously, we demonstrated a two-layer, submicrometer-scale overlap junction fabrication process suitable for qubits with long coherence times. Here, we extend the overlap junction fabrication process to micrometer-scale junctions. This allows us to fabricate other superconducting quantum devices. For example, we demonstrate an overlap-junction-based Josephson parametric amplifier that uses only 2 layers. This efficient fabrication process yields frequency-tunable devices with negligible insertion loss and a gain of ~ 30 dB. Compared to other processes, the overlap junction allows for fabrication with minimal infrastructure, high yield, and state-of-the-art device performance.